This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. A primary goal of this collaboration is to determine what physical changes are responsible for differences in scattering exhibited by in vivo dysplastic and non-dysplastic cervical tissue. The use of perturbation Monte Carlo (pMC) methods is critical to understanding the relationship between these physical changes and measured light scattering properties. Use of such methods will not only produce dramatic gains in computational efficiency but also improve the accuracy in model precitions. physical changes lead to the scattering changes we measure in vivo, is to be achieved.